Mn doped NiO nanostructured materials with composition Ni 1-x Mn x O 1-δ (where x = 0.01, 0.03, 0.05, 0.07, 0.09) (MNO) were prepared by simple facile chemical synthesis route. The structural, particulate and microstructural characteristics of the Mn-doped NiO nanostructures were studied by studied by XRD, FTIR, particle size analysis, EDAX, SEM and HRTEM techniques. The XRD peaks of all the materials were indexed to the face-centred cubic (FCC) crystalline structure. FTIR spectra revealed the presence of NiO bending vibration mode between 432.07 to 492.83 cm-1. Particle size patterns and SEM photographs confirmed the presence of nanosized grains apart from few bigger sized grains. The diameter of grains was mostly found to be in the range of 30.04 to 591.16 nm. Presence of appropriate composition of elements was confirmed by EDAX data. Polycrystalline behaviour of Ni 0.95 Mn 0.05 O 1-δ was exhibited by HRTEM data. The electrochemical phenomena of Ni 1-x Mn x O 1-δ were studied by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance measurements in 6 M KOH aqueous solution. Among the samples studied, Ni 0.95 Mn 0.05 O 1-δ electrode exhibited maximum specific capacitance of 369.6 Fg-1 at a current density of 0.5 Ag-1. From the characterization data, Mn-doped NiO nanostructures appear to be the good electrode materials for electrochemical supercapacitor applications.